ML17059C597
| ML17059C597 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 03/24/1999 |
| From: | Hood D NRC (Affiliation Not Assigned) |
| To: | Mueller J NIAGARA MOHAWK POWER CORP. |
| References | |
| TAC-MA4491, NUDOCS 9903290146 | |
| Download: ML17059C597 (16) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 March 24, 1999 S~-x>
Mr. John H. Mueller Chief Nuclear Officer Niagara Mohawk Power Corporation Nine Mile Point Nuclear Station Operations Building, Second Floor P.O. Box 63 Lycoming, NY 13093
SUBJECT:
CORE SHROUD REINSPECTION PLAN FOR REFUELING OUTAGE 15, NINE MILEPOINT NUCLEAR STATION, UNIT NO. 1 (TAC NO. MA4491)
Dear Mr. Mueller:
By letter dated December 30, 1998, Niagara Mohawk Power Corporation (NMPC) submitted its plans for reinspecting the core shroud at Nine Mile Point Nuclear Station, Unit 1 (NMP1) during refueling outage No. 15 (RFO15), scheduled to begin about April 14, 1999. The plans addressed reinspection of the shroud repair components, the shroud repair anchorages, and the shroud's horizontal, vertical, and ring segment welds. The reinspection details included the inspection methods to be used.
NMPC stated that the inspection scope will meet or exceed the inspection scope recommended for a repaired shroud in BWRVIP-07, "BWR Vessel and Internals Project Guidelines for Reinspection of BWR Core Shrouds," and that all examinations will be performed in accordance with the requirements in BWRVIP-03, "Reactor Pressure Vessel and Examination Guidelines." The proposed reinspection plan is further summarized below:
Shroud Re air Assemblies A visual inspection, using a combination of VT-3 and EVT-1, will be performed from both sides of each of the four entire shroud repair assemblies (a.k.a., tie rod assemblies).
The VT-3 willverify that all tie rod assembly components remain in their as-installed condition. The EVT-1 will be used to inspect the latches, top support, and the tie rod assembly anchorage locations.
In addition, the tightness of the tie rod assemblies willbe verified by visual examination and the tie rod nuts willbe retorqued to the original installation torque.
Vertical Welds The inspection will be performed on all shroud vertical welds. The vertical welds are designated as V3, V4, V7, V8, V9, V10, V11, V12, V15 and V16. All accessible areas of each weld willbe inspected by ultrasonic testing (UT) or a combination of UT and enhanced visual examinations (EVT-1).
3.
UT inspections willbe performed on all the accessible portions of the ring segment.
welds. The ring segment welds are designated as V1 and V2 in the upper shroud ring, 9903290146 990324 PDR ADOCK 05000220 8 -"-'-""va ptwe pr q p t'".
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J. Mueller V5 and V6 in the shroud top guide ring, and V13 and V14 in the shroud core plate ring.
~If a ring segme'nt weld cannot be located, a UT inspection of an amount of ring circumference determined to be sufficient to verify the effectiveness of the shroud horizontal weld repair willbe performed.
Horizontal Welds 4.
The shroud horizontal circumferential welds are structurally replaced by the shroud repair assemblies and, except for shroud support welds H8 and H9, do not need to be inspected.
5.
An EVT-1 will be performed to reinspect the flaw indications at shroud support weld H8.
The flaw indications, detected during 1995 (RFO13) and 1997 (RFO14), are small and the results of flaw evaluation showed that these flaws do not require UT inspection until the year 2001 (RF016).
6.
The shroud support weld H9 will be inspected by EVT-1 from the annulus in accordance with the recommendations in BWRVIP-38, "BWR Shroud Support Inspection and Flaw Evaluation Guidelines."
The NRC staff has reviewed NMPC's submittal and has determined that the core shroud reinspection plan for NMP1 RFO15 follows the guidelines in BWRVIP-07 and the NRC staff's recommendations in its associated safety evaluations dated September 15, 1997, and April27, 1998. Therefore, the proposed core shroud reinspection plan is acceptable.
The NRC staff is in the final phase of completing its review of BWRVIP-38, and on the basis of that review, finds BWRVIP-38 to be acceptable for use regarding inspection of shroud support weld H9 during NMP1 RFO15.
NMPC should incorporate the NRC staff's recommendations once the NRC has issued its safety evaluation on BWRVIP-38.
NMPC's submittal (page 1 of Attachment) also states that "[p]rovided the inspection results are bounded by the existing Nine Mile Point Unit 1 (NMP1) structural analysis following the planned inspection, no vertical weld repairs willbe installed....". The NRC staff notes that the results of NMPC's previous estimation of the fluence level showed that the maximum fluence level at the end of the current fuel cycle would be near the threshold value of 5 x 10" n/cm'in some parts of the shroud.
This threshold value of fluence is derived from the limiting conditions of applicability of the crack growth rate data.
Exceeding the fluence threshold value, as may eventually occur in some shroud regions, would impact the bounding crack growth rate used in the flaw evaluations.
NMPC should address fluence level distribution corresponding to the end of the proposed operating period until the next reinspection, and its impact upon the bounding crack growth rate used in the flaw evaluations, to determine whether or not repairs are required based upon NMPC's flaw evaluations.
On the basis of the BWRVIP commitment on behalf of the BWR Owner's, we assume that you are following the BWRVIP program for inspection, evaluation, and repair of the other reactor vessel internals at NMP1. Ifnot, we request that you inform us promptly of any significant.
exceptions regarding RFO15 activities.
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J. H. Mueller The NRC staff acknowledges your commitment to define the scope of the core shroud reinspection for RFO16 at least 3 months before the start of RFO16.
Ifyou have questions regarding this letter, contact me by phone at (301) 415-3049 or by electronic mail at dsh@nrc.gov.
Sincerely, Darl S. Hood, Senior Project Manager Project Directorate I-1 Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-220 cc:
See next page
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March 24, 1999 J. H. Mgeller The NRC staff acknowledges your commitment to define the scope of the core shroud reinspection for RFO16 at least 3 months before the start of RFO16.
Ifyou have questions regarding this letter, contact me by phone at (301) 415-3049 or by electronic mail at dsh@nrc.gov.
Sincerely, Original signed by:
Darl S. Hood, Senior Project Manager Project Directorate I-1 Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-220 cc:
See next page DISTRIBUTION:
See attached page DOCUMENT NAME: G:'lNMP15LTR24491.WPD
- See previous concurrence To receive a copy of this document, indicate in the box: "C" = Copy without attachment/enclosure "E" = Co with attachment/enclosure "N" = No co OFFICE PH:PDI-1 E
LA:PDI-D:PDI-1 BC:EMCB BCPRSXB*
WAHE DHood/rsl SLittl 03/
99 DATE 03/
/99 SBsjws 03/
/99 Official Record Copy ESulllvsn 03/
/99 JWormiol 03/23/99
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March 24, 1999 J. H. Mueller The NRC staff acknowledges your commitment to define the scope of the core shroud reinspection for RFO16 at least 3 months before the start of RFO16.
Ifyou have questions regarding this letter, contact me by phone at (301) 415-3049 or by electronic mail at dsh@nrc.gov.
Sincerely, Original signed by:
Darl S. Hood, Senior, Project Manager Project Directorate l-1 Division of Licensing Project Management Office of Nuclear Reactor Regulation-Docket No. 50-220 cc:
See next page DISTRIBUTION:
See attached page DOCUMENT NAME: G:iNMP1iLTR24491.WPD
- See previous concurrence To receive a copy ofthis document, indicate in the box: "C" = Copy without attachment/enclosure "E" = Co with attachment/enclosure "N"= No co OFFICE PM:PDI-1 E
LA:PDI-NAME DNood/rsl SLIalii D:PDI-1 SBajwa BC:EMCB ESUIIivan BC:RSXB*
JNormiel DAlE 03/
/99 03/
99 03/
/99 Official Record Copy 03/'99 03/23/99
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John H., Mueller Niagara Mohawk Power Corporation Nine Mile Point Nuclear Station Unit No. 1 CC:
Regional Administrator, Region I
U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 Resident Inspector U.S. Nuclear Regulatory Commission P.O. Box 126 Lycoming, NY 13093 Charles Donaldson, Esquire Assistant Attorney General New York Department of Law 120 Broadway New York, NY 10271 Mr. Paul D. Eddy State of New York Department of Public Service Power Division, System Operations 3 Empire State Plaza Albany, NY 12223 Mr. F. WilliamValentino, President New York State Energy, Research, and Development Authority Corporate Plaza West 286 Washington Avenue Extension Albany, NY 12203-6399 Mark J. Wetterhahn, Esquire Winston & Strawn 1400 L Street, NW Washington, DC 20005-3502 Gary D. Wilson, Esquire Niagara Mohawk Power Corporation 300 Erie Boulevard West
- Syracuse, NY 13202 Supervisor Town of Scriba Route 8, Box 382 Oswego, NY 13126
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DATED CORE SHROUD REINSPECTION PLAN FOR REFUELING OUTAGE 15, NINE MILE POINT NUCLEAR STATION, UNIT NO. 1 Docket File PUBLIC PDI-1 Reading J. Zwolinski S. Bajwa S. Little D. Hood OGC G. Hill (2), T-5 C3 ACRS A. Blough, Region I
W. Koo R. Hermann K. Wichman E. Sullivan J. Rajan K. Manoly L. Lois J. Wermiel cc: Plant Service list
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DATED:
CORE SHROUD REINSPECTION PLAN FOR REFUELING OUTAGE 15, NINE MILE POINT NUCLEAR STATION, UNIT NO. 1
~(glje333lg PUBLIC PDI-1 Reading J. Zwolinski S. Bajwa S. Little D. Hood OGC G. Hill (2), T-5 C3 ACRS A. Blough, Region I
W. Koo R. Hermann K. Wichman E. Sullivan J. Rajan K. Manoly L. Lois J. Wermiel cc: Plant Service list
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